Previous aircraft designs have been provided with multiple openings/apertures on the outer mold line of the aircraft fuselage in order to supply air to various aircraft systems. However, it is generally desirable to reduce the number of openings on the outer mold line of the aircraft fuselage. The provision of multiple openings in the outer mold line may result in an undesirable impact on aircraft design and performance. For example, multiple openings in the outer mold line may increase drag, increase vulnerability, and/or increase maintenance due to foreign objects/debris entering the openings.
The number of openings on the outer mold line required to provide air to the aircraft systems may be reduced by providing an air off-take within the engine inlet. However, it has been found that such an arrangement can result in undesirable aircraft operational characteristics. For example, when the aircraft is traveling below a certain airspeed (e.g., ground operation and low-mach flight) suction in the engine intake due to engine operation can prevent air from flowing into the off-take. In some instances, the suction can be great enough to suck air out of the off-take.